Shut-off arrangement for mercury vapor systems



Aug. 19, 1952 Q, WOOD TA SHUT-OFF ARRANGEMENT FOR MERCURY VAPOR SYSTEMSFiled May 31, 1951 AIR REMOVAL 16; AIR REMOVAL l XX): 20 Marco/er sum mH k l lla Inventor's: Orla L.Wood, Harold Nhackett,

' Their Attorney.

Patented Aug. 19, 1952 UNITED STATES; PATE SHUT-OFF ARRANGEMENT FORVAPOR SYSTEMS Orla L. Wood, S che Hackett, Ballston, Electric Company,

NT. OFFICE.

MERCURY nectady, I and Harold N. Y.,' assignors to General a corporationof New York Application Mayer, 1951, serial No. 229,148

This invention relates to mercury vapor power-plants, particularly to anarrangement for disconnecting a component from a mercury vapor systemwithout permitting ineleakage of air into the system and without thenecessity-for shutting down the entire plant.

One of the few binary fluid cycleswhich has taken to preserve the purityof the-mercury.

Even though the system is'thoroughly cleaned before being put intooperation, it is foundthat the mercury inevitably picks up a substantialamount of, dust and other dirt particles; and inspite of the exercise ofgreatest caution there will be a-certain amount of leakage of air intothe system with. the resulting accumulation of dirt during normaloperation of the power plant. This makes it'necessary to provide meansfor continuously removing whatever dust-and other dirt particles mayaccumulate in the system.

One way to eiTect this continuous, removal of dirt from the mercurysystem is to create a vacuum in the mercury sump sufilcient to'elfectevaporation of some of the mercury, the evaporating vapors serving tocarry all the impurities to an air removal cooler" where the mercuryvapor is condensed and the non-condensible picked up in the boiler,turbine, etc. is drained to V which is sealed air-tight gases are drawnoil by an air removal vacuumpump. This type of cleaning system isdisclosed in United States Patent 2,196,003, issued in the name of O. L.Wood on April 2, 1940, and assigned to the same assignee as the presentapplication.

In connection with such a cleaning system, a

further problemarises from the necessity for I periodically removing theaccumulated impurities from the air removal cooler. 'Itis, of course,highlydesirable that this be accomplished without completely shuttingdown the mercury turbine power plant.

Accordingly, an object of the present invention is to provide animproved mercury cleaning system of the type described having specialmeans.

for effecting isolation of the air removal cooler 5 Claims. (01. -36) 2r so that it may be opened and cleaned without shutting down the entireplant.

A further object is to provide an isolating arrangement of the typedescribed which does not depend on mechanical valves to seal the vacuum,yet-is capable of positively preventing the en-. trance of air into thesystem during the process of isolating and cleaning the air removalcooler.

Other objects and advantages will become apparent from the followingdescription taken in 7 connection with the accompanying drawing in whichthe single figure represents diagrammatically a mercury turbine powerplant having means for isolating the air removal cooler in accordancewith the invention.

Generally, the invention is practiced by providing in each-vacuumconduit connected to the air removal cooler a U-shaped trap, withspecial means for filling and draining these liquid seals when itisdesired to isolatethe air removal cooler.

Referring now more particularly to the draw ing, the invention isillustrated as applied to a mercury turbine power plant comprising amercury boiler I supplying motive fluid to a turbine 2, the exhaust fromcondenser-boiler pose of generating steam for driving a steam turbine orfor other purposes. 7

Liquid mercury collecting in the bottom of the condenser boiler 3,together with dirt particles that maintained in the condenser-boiler 3.This 7 higher; vacuum in the sump is produced by a conduit 6 connecteddirectly to cooler I, and causes some of the liquid mercury in the sumpto flash into vapor and be drawn oil to the cooler, carrying with it thedust and other dirt' -which accumulates on the surface of the1iquid,mercury-in the sump. Thus, the sump serves the double purpose ofseparating the dirt or dust from the mercury and as a reservoirsupplying the boiler feed pump 5, which returns liquid to the boiler Ithrough the feed conduit 5a.

In accordance with the invention disclosed in the above-identifiedpatent to Wood 2,196,003, the dirt or dust is removed from the mercurysump 4 by way of a vacuum conduit 6 communicating with the air removalcooler I as described above. Similarly, air and entrained gasesseparating in the condenser-boiler 3 may which is condensed in a"3,-which also serves the purin the cooler i eiiects condensation of themercury, which falls to the bottom of cooler I and is drained throughthe return conduit H having a U-seal I la. The remaining uncondensedgases are drawn off through conduit 42 having a valve {2a to the airremoval vacuum pump l3, which discharges to atmosphere through asuitable vent H. To provide access for cleaning the cooler I, aremovable clean-out door It is provided. This i carries an atmosphericvent having .a, manu-.

ally controlled bleed valve ll. A vacuumgaugeei I8 is located convenientto the valve I! so that the operator can bring the air removalco'oler:to atmospheric pressure at a desired rate, andc so that the accessopening cover [5 will not be removed until the pressure inside thecooler .7 is atmospheric.

In accordance with thein'vention, each vacuum" line connected to thecooler l, specifically-the vapor draw-air Y conduits 6, 8, are providedwith U-seals 19', 23 respectively; During normal" oper-- ation; theseU-scals" are kept free of condensed liquid by a gravity drain conduit-2| having branches connecting the lowermost portion of each U-seal withthe interior of the cooler -!,or

with some other portion of the system to which the sealing. liquidcanldrain when the manual shut-offvalve 22 is opened. It willbe obviousthat the arrangement of the U-sealsand the sump l 'must be such'that innormal'operation the liquid level in the sump never rises highenough toenter the U-s'eals' from the cooler 1;

The means for filling the liquid'U-seals comprises an elevated supplytank 23 containing liquid mercury maintained at atmospheric pressure bythe vent 2t. A gage glass 25 or-equivalent liquid level indicating meansshows the levelof mercury in the reservoir 23. The mercury used to sealthe vacuum conduits 6,8 is returned to the-reservoir 23by a returnconduit-26 communicating with the boiler feed conduit 5d, and

containing a valve 27. Sealing liquid is supplied from reservoir 23 byway of a. conduit 28 containing a valve 29'. This: conduit 28 mayconveniently be connected to the branched drain conduit 2!- as clearlyshown in the. drawing.- It

is to be noted that the supply conduit 28 is provided with a U-seal28a;

The manner in which this system is employed to positively isolate theair removal cooler 1 without using any mechanical valves in the vacuumconduits will-be seen from the following.

When it is desired'to clean out the air removal cooler I, the seal drainvalve 22" is closed, and the seal liquid supply valve 291 opened'so thatliquid mercury flows from the reservoir 23 through conduit 28 to fillthe U-seals I9, 20, until the shorter legs 19b, 20a, are filled andliquid beginsto overflow into the cooler 'l.- The air removal pump valveI2 is then closedand the bleed valve I! opened to slowly admit air fromthe atmosphere to' cooler 1. As thepressure in cooler 1 builds up toatmospheric, the liquid mercury in the U-seals I9, 28 rises in thecomparatively long right-hand legs- Ma, 2112)} until the heightof themercuryfcolumn in'these legs is sufiicient to balance the vacuumexisting in the mercury system during normal operation. This mercurycolumn in the U-seallegs 19a; 206, thus preserves the normal vacuum .inthe mercury sump 4 and the condenser-boiler 3, and the mercury vaporpower plant can continue to operate while the clean-out door 15 isremoved and the accumulated dirt removed from cooler l. Similarly, theU-seal Ha seals the drain conduit H.

To put the air removal system back into service, the clean-out doorcover i5 is. replaced and the bleed valve ll closed. The vacuum pumpvalve l2a' is then opened and the pump I3 brings the air removal cooler1 down to the normal vacuum on the system. The valve 29 is then closedand the scal'drain'valve ZZopened so that the liquid in' the. U -sealsI9, 2%) flows into the cooler 1 through drain conduit 2 L This, ofcourse, means that thetotalamount of mercury in the system has, beenincreased by the amount employed to seal the traps I9, 28. In order toreturn the amount of-working fluid to its normal value, valve 21 isopened and mercury from the boiler feed conduit 5c permitted to flowback into reservoir 23 until the level therein, as indicated by. gage25, returns to its {previous normal value."

While it is'tr'ue that, during normal-operation, some-air may leak intocooler 1 through the" mechanicalvalve [1, any such leakage-air will be"?directly expelled'by pump1l'3. During the process of isolating cooler Iand cleaning the'dirt therefrom,'the cooler is entirely isolated fromthe vacuum: parts of 'the ,systemtby liquid-filled" U-seals,no-mechanical valves being present to: introduce the possibility thatdirt may prevent'i the valves-from seating tightly and-thereby per=' mitair to enter the system:

Itwill be' seen that the'invention provides a mechanically simplearrangement for effectively I sealing the-vacuum 'lines of amercury'vap'or powerplantin-orde'rthat one component thereof" may beremoved from the system for cleaning or other maintenance purposes;

While only one embodiment of the invention? has been describedspecifically herein; it will be apparent to thoseskilled in the artthatmany: substitutions of equivalents andmodifications":

It is, of course, desired to cover by theappendedclaims all such changesas fall,

may be made".

within the-true spirit and scope of the invention.

What-we claim-as new-and desire to secure by Letters Patent of theUnited States is:

1. Ina mercury vapor powerplant having in series a boiler feed pump,mercury boiler, turbine, condenser-boiler, and mercurysump maintainedunder-vacuum by "a second pump for removing non-condensible gases fromthe system and an' air removal cooler connected-in series between thevacuum pump and the condenser-boiler'and betweenthe vacuum pump and thesump respectively, the combination of means for isolating the airremoval coolerfrom the vacuum portions of the ystem comprising a firstconduit for draw-' ing off hon-condensible gases from thecondenserboiler and including a first U-section, .a second conduit' fo'rdrawing .off non condensible gases from the sump and including'a secondU-section, the lowermost portion of said U-sections being above thebottom of the air removal cooler and connected, thereto by a gravity.drain conduit,

first shut-01f valve means in said drain conduit, an elevatedmercuryreservoir vented to-atmos--- phere and connected by a seal supplyconduit. to

said drain conduit between the shutofi valve and Y the U-sections, saidseal supply conduit including a third U-section and a second shutoffvalve between the third U-section. and the reservoir, a seal liquidreturn conduit for bleeding mercury-.- from the boiler feed pump back tosaid reservoir,

third valve means in said seal liquid return conduit, and valved ventmeans for bringing the air removal .cooler up .to atmospheric pressure,

whereby the air removal cooler may be isolated supply valve to fill allthree U-sections, after which said valved vent may be opened to'breakthevacuum in the air removal: cooler, the cooler being returned toserviceby closing the seal liquid supply valve and opening the drainvalve to empty the first and second U-sections into the cooler afterwhich the quantity of mercury in the system may be restored to normal byopening said third valve to admit mercury from the feed pump to the sealliquid reservoir.

2. In a mercury vapor powerplant having in series a boiler feed pump,mercury boiler, turbine, condenser-boiler, and a mercury sump maintainedunder vacuum by a second pump for removing non-condensible gases fromthe system and an air removal cooler connected in series between thevacuum pump and sump, the combination of means for isolating the airremoval cooler from the sump comprising a conduit for drawing ofinon-condensible gases from the sump and including a U-section with oneleg connected to the air removal cooler, a gravity drain conduitconnecting the lowermost portion of said U-section with the air removalcooler, first shutoff valve means in said drain conduit, an elevatedmercury reservoir vented to atmosphere and connected by a conduit forsupplying sealing liquid to the U-section, the seal supply conduithaving a second U-section and a second shutoil valve, and valved ventmeans for bringing the air removal cooler up to atmospheric pressure,whereby the cooler may be isolated from the sump by closing'the gravitydrain valve and opening the seal liquid supply valve to fill saidU-sections, after which the valved vent may be opened to break thevacuum in the air removal cooler, the cooler being returned to serviceby closing the seal liquid supply valve and opening the gravity drainvalve to empty the first U-section into the cooler.

3. In a mercury vapor plant having in series a boiler feed pump, amercury boiler for enerating mercury vapor under pressure, a mercuryvapor energy consumer, a condenser-boiler and a mercury sump maintainedunder vacuum by a second pump for removing non-condensible gases fromthe system, and an air removal cooler connected in series between thevacuum pump and the sump, the combination of means for isolating the airremoval cooler from the sump comprising a vacuum conduit for drawing offnon-condensible gases from the sump and including a U-seal sec- :tion,the lowermost portion of said U-seal being above the bottom of the airremoval cooler and connected thereto by a gravity drain conduit, firstshut-off valve means in said drain conduit, a mercury reservoir locatedsubstantially above the level of the air removal cooler and vented toatmosphere, a seal liquid supply conduit for conducting liquid from saidreservoir to the lowermost portion of said U-seal, said seal supplyconduit including a second U-seal and a second shut-oil valve betweenthe second U-seal and the reservoir, a seal liquid return conduit forbleeding mercury from the high pressure side of the system back to theseal liquid reservoir, third valve means in the seal liquid returnconduit, and valved vent means for bleeding air into said .cooler forbringing the pressure therein up to atmospheric, whereby the air removalcooler may be isolated from the mercury sump by closing said first drainvalve and opening the seal liquid supply valve to fill said U-sealsections, after which said valved'vent may be opened to break the vacuumin the air removal cooler, the cooler being returned to service byclosing the seal liquid supply valve and opening the drain valve toempty the first U-seal into the cooler, after which the quantity ofmercury in the system may be restored to normal by opening said thirdvalve to admit mercury from the high pressure portion of the system tothe seal-liquid reservoi'rj I 4. In a thermal energy transfer andconversion system having hydraulic circuits filled with a vaporizableliquid the purity of which must be carefully preserved by continuouslyremoving dirt therefrom during normal operation, said hydraulic circuitsincluding a liquid sump maintained under a substantial vacuum by an airremoval pump and having an air removal cooler in series between the pumpand sump, the combination of means for isolating the air removal coolerfrom the sump comprising a vacuum conduit, for drawing offnon-condensible gases from the sump and including a U-seal section, thelowermost portion of U-seal being above the bottom of the air removalcooler and connected thereto by a gravity drain conduit, first shut-offvalve means in the drain conduit, a liquid reservoir locatedsubstantially above the level of the air removal cooler and vented toatmosphere, a seal liquid supply conduit for conducting liquid from saidreservoir to the lowermost portion of the U-seal, the seal supplyconduit including a second U-seal and a second shut-off valve, andvalved vent means for bleeding gas into the cooler for bringing thepressure therein up to atmospheric, whereby the air removal cooler maybe isolated from the sump by closing the gravity drain valve and openingthe seal liquid supply valve to fill said U-sections, after which thevalved vent may be opened to break the vacuum in the air removal cooler,the cooler being returned to service by closing the seal liquid supplyvalve and opening the drain valve to empty the first U -seal into thecooler.

5. In a thermal energy transfer and conversion system having hydrauliccircuits filled with a vaporizable liquid the purity of which must becarefully preserved by continuously removing dirt therefrom duringnormal operation, said hydraulic circuit including a liquid sumpmaintained under a substantial vacuum by an air removal pump and havingan air removal cooler in series between the pump and sump, thecombination of means for isolating the air removal cooler from the sumpcomprising a vacuum conduit for drawing off non-condensible gases fromthe sump and including a U-seal section, a drain conduit communicatingwith the lowermost portion of the U-seal, first shut-off valve means insaid drain conduit, a source of liquid located substantially above thelevel of the U-seal, a sealing liquid supply conduit for conductingliquid from said reservoir to the U-seal, the seal supply conduitincluding a second U-seal and a second shut-off valve, and valved ventmeans for bleeding gas into the cooler to bring the pressure therein upto atmospheric, whereby the air removal cooler may be isolated from thesump by closing the drain valve and opening the seal liquid supply valveto fill said U-seals, after which the valved vent may be opened to breakthe vacuum in the air removal cooler, the cooler be- 7 ingtrebfirnedtry-service by. closing the'seal liquid' Number supply I valveandmpenin'g the drain valve. 1,436;174' ORL'A'L. WOOD; 2,121,599

HAROLD N HACKETT. 2,196,003

, k 5 v REFERENCES CITED Thgfollowing references-are of recordinthmurlber 9, fil p th'i'syatent: 2 2 32 v UNITEDSTATES PATENTS 1D 70.53271Nuniber Name-" Date 906,312 Shaw Dec. 8, 1908' Name. Date JohmssonNov;21 ,1922" Kilgoreet; a1 June 21;1938} Wood Apr."2,'1910" FOREIGNPATENTS Country Date" -Grea-t Britain July '4; 1932' France Sept.29;1925

Germany Apr. 22 1941-

